Sandpaper backing disk



Nov. 26, 1963 H. H. LEGG SANDPAPER BACKING DIsK 2 Sheets-Sheet l Filed Feb. 7. 1961 9B. ww a H. w W. wn m W fi w HHI' A/M/o.

United States Patent fiice 3,1 l '1,792 Patented Nov. 26, 1963 w 3,111,7'2 SANDPAPER BACKING DISK Harvey H. Legg, 507 Elizabeth Ave., Hattiesbnrg, Miss. Filed Feb. 7, 1961, Ser. No. 87,585 3 Claims. (Cl. 51-177) This invention relates to a novel and useful sandpaper hacking disk and more part'icularly to a sandpaper hacking disk specifically adapted for use with rotary type sanders |utilized to san'd 'fiooring Surfaces.

Most flooring surfaces are provided with peripheral shoe moldings and in most instances rotary Sande-rs utilized to Sand these fiooring Surfaces are provided with housings generally circular in plan which enclose the rotary disk to which the sandpaper -is secured. The housing of the Sander is suitably supported by means of Wheels for movement across the flooring surface and the height of the disk of the sanding machine may be adjusted re'lat'ive to the flooring surface by means of suitable adjusting mechanisms carried by the support Wheels of the Sander housing. Most rotary sanders are provided with sanding disks slightly smaller than the diameter of the generally circular configuration of the Sander housing. The sandpaper secured to the sanding disk is slightly larger than the disk and is adapted to extend radially outwardly beyond the peripheral edge of the disk and heneath the lower edges of the generally circular housing of the sander in order that the -flooring may he sanded immediately adjacent the shoe molding disposed about its periphery. The sanding disks are normalily constructed of a resilient material such as ruhher and are thus relatively thick. The outer marginal portions of the sandpaper extending beyond the peripheral edges of the resilient sanding disk rely mostly upon centrifugal force in order to apply pressure to the area of the flooring immediately adjacent the shoe mold'ing. Inasmuch as this outer marginal portion of the sandpaper carried by the sanding disk is not provided With suitable hacking, after a short period of use this margina'l portion hecomes frayed and is not efficient in sanding the area immediately adjacent the shoe molding. Accordingly, if the flooring is to be sanded correctly, the sandpaper must he changed quite frequently and before the center portion of the sandpaper has been fully used or the areas immediately adjaccent the shoe molding are properly not sanded. Thus, in order to complete a sanding operation and to Sand the area of the floor immedi-ately adjacent the shoe molding a 'considerahle amount of sandpaper is wasted.

There have in the past been attempts at providng a hacking disk for sandpaper provided with a beveled outer periphery edge portion so that the extreme outer marginal portions of the hacking disk may pass beneath the lower ends of the generally circular side walls of the housing of the Sander. This ho'wever results in the rubber hacking disk scored in a relatively short time by the undersurfaces of the side walls of the housing as the Sander is tilted to one side or the other which causes the hacking disk to bend and contact the lower ends of the Sander housing side walls.

It is the main object of this invention to provide a hacking disk for a rotary fioor Sander constructed in a manner whereby the disk may be constructed of a diameter sufficient to position the outer peripheral edges in alignment with the outer peripheral surfaces of the generally cylindrical or side walls of the sander housing immediately adjacent the lower ends thereof in order that the enti're area of the disk of sandpaper carried by the hacking disk wil'l have Sufiicient hacking Support.

A further object of this invention, in accordance with the 'immediately preceding object, is to provide a hacking disk constructed of a metallic substance but in a manner Whereby individual outer portions of the hacking disk may ilex without resulting in flexing of the remainder of the hacking disk.

Still another object of this invention is to provide a hacking disk which will aid in the circulation of cooling -air about the motor of the Sander.

Another object of this invention, in accordance with the immediately preceding object is to provide a sanding disk which will provide a cushion of the air between the outer peripheral portions of the hacking disk and the Sandpaper disk secured thereto Wherehy a more efficient and even pressure may he eifected of the sandpaper on the fiooring being sanded therehy enahling the life expectancy of the sandpaper disk to be greatly extended.

A final object to he specifically enumerated herein is to provide a hacking disk which 'Will conform to conventional forms of manufacture, he of simple construction and easy to use So as to provide a device that will he economically feasihle, long lasting and relatively trouhle free in operation.

These together with other objects and ad'vantages which will become subsequent'ly apparent reside in the details of construction and operation as more fully hereinafter deScr-ibed and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a bottom plan view of the hacking disk of the instant invention;

l`FIGURE 2 is a side elevational view of the hacking disk;

FIGURE 3 is a side elevational view of the hacking disk shown mounted on a rotary type of Sander and with a disk of sandpaper secured thereto;

FIGURE 4 is an enlarged fragmentary Vertical Sectional view taken suhstantia'lly upon a plane passing through the longitudinal center line of the Sander illustrated in FIGURE 3.

Referring now more specifically to the drawings the numeral 10 generally designates a conventional form of electric rotary sander. The sander 10 includes a housing generally referred to by the reference numeral -12 which may be formed integrally with the end wall 14 of the Sander 10. The Sander 10 includes an output shaft 16 which iS suitahly journalled by means of bearings (not shown) housed within the Sander 10'. The housing 12 includes an upstanding bore 18 through which the lower end of the output shaft 16 is loosely received. The housing 12 includes upstandin'g generally circular side walls 20 having lower edges 22.

The terminal end portion of the output shaft y16 is diametr'ically reduced and externally threaded as at 24.

The hacking disk of the instant Iinvention .is generally referred to by the reference numeral 26 and includes a circular hub generally referred to by reference numeral 28'. The hub 28 has -an axial threaded bore 30 formed therethrough and the lower terminal end portion of the output shaft 16 is threadedly engaged in the bore 30.

The hub 28 is generally circular in plan and has an outer face 32 in which there is formed an outer annular recess 34 which defines the outer marginal portions of the hub 28. A metallic hacking disk generally referred to by the reference numeral 36 is provided and is generally circular in plan. The disk 30 has a plurality of circumferentially disposed openings 38 formed therein spaced distances inwardly of the outer marginal edge portion of the disk. A plurality of slots 40 indicate each of the openings 38 with the outer periphery of the disk 36 and the slots 40 are curved and have their outer ends disposed in trailing positions relative to their inner ends in the direction of rotation of the hacking disk 26. The

A thin resilient disk 36 has a centrally disposed opening 42 3 formed therein which receives the center portion 44 of the hub 28 defined by the recess 34. A hacking plate 46 and a stiffening plate 48 are each also provided with centrally disposed openings referred to by the reference numerals 50 and 52 which are aligned with the opening 42 and also receive the central portion 44 of the hub 28. Any convenient form of fasteners 54 are passed through the stacked plates 40 and 48 and through the thin resilient disk 36 in order to secure the plates and disk to the hub 28.

The terminal end portion of the output shaft 16 is provided with a threaded blind hore 56 in which a threaded fastener 58 is threadedly engaged in order to secure a disk of sandpaper generally referred to by the reference numeral 60 to the hacking disk 26. The disk of sandpaper 60 includes a hacking disk 62 with a covering of granular material 64 secured to one face thereof.

It will be noted that the openings 38 are of a greater diameter than the width of the slots 40 and that the hacking plate 46 terminates a spaced distance from the outer peripheral edge of the resilient disk 36. In addition, it will be noted that the stiffening plate 48 terminates a spaced distance from the outer peripheral edges of the hacking plate 46.

In operation, the Sander is operated across the flooring 66. Rotation of the output shaft 16 rotates the backing disk 26 and the outer marginal portions of the resilient disk 36 are thin enough to pass between the lower surfaces 22 of the side walls 20 and the flooring 66 to ahut against the shoe molding 68.

The sandpaper disk 62 is of the same size as the resilient disk 36 and therefore also extends outwardly to the outer surfaces of the side walls 20 and abuts against the shoe molding 68.

Upon rotation of the disk 26 in a counterclockwise direction in FIGURE 1 of the drawings the air within the slots 46 is forced outwardly through the slots by centrifugal force thus creating a reduced pressure area in the openings 38. This reduced pressure area creates a reduced pressure in the downwardly opening recess 70 formed by .the housing 12 and draws air downwardly from the motor of the sander 10 through the space between the output shaft 16 and the walls of the opening 18. In this manner, circulation of cooling air is drawn through the motor of the sander 10 and passes outwardly between the confronting surfaces of the sanding disk 60 and the resilient disk 36 wherehy the sanding disk 60 is cushioned by a layer of air. The air cushion effected by the rotation of the disk 26 greatly increases the life of the sandpaper disk 60 and inasmuch as the outer marginal portion of the resilient disk 36 is divided into resilient fingers 72 by means of the slots 40, each of these resilient fingers may fiex independently of the other wherehy a more even distribution of pressure is eifected on the outer peripheral portions of the sandpaper disk 60. Inasmuch as the sandpaper disk 60 and the resilient disk 36 extend outwardly to the outer surfaces of the side walls 20 of the housing 12, the flooring 66 may be sanded immediately adjacent the shoe molding 68.

The foregoing is considered as illustrative only of the principles of the invention. Further,` since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and descrihed, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In combination with a rotary Sander of the type having a Vertical output shaft whose lower end is enclosed by a generally circular housing having upstanding peripheral side walls defining a downwardly opening recess, a sandpaper hacking disk, said hacking disk having one side adapted to have a thin disk of sandpaper secured thereto, the other side of said hacking disk including means securing said disk to said output shaft for rotation therewith, said one side comprising the outer surface of a thin resilient disk, said disk having circumferentially disposed openings formed therein, a plurality of generally radial slots formed therein communcating at least some of said openings with the outer peripheral edge of said resilient disk, and a thin outer marginal edge portion extending closely heneath the lower edges of said housing, a circular hacking plate, the inner face of said resilient disk being secured over the outer face of said hacking plate, said hacking plate being of a diameter substantially smaller than said resilient disk and having its outer peripheral edge portion disposed inwardly of said walls, said openings being of a diameter greater than the width of said slots, said slots being curved and their outer ends being adapted to trail the inner ends thereof in the direction of rotation of said hacking disk, a circular stiffening plate, the inner face of said hacking plate being secured over the outer face of said circular stiffening plate, said stiffening plate being of suhstantially smaller diameter than said hacking plate, said openings being disposed inwardly of the outer peripheral portions of said stiffening plate and said stiifening plate and said hacking plate having aligned circumferentially spaced openings formed therethrough in registry with said openings formed in said resilient disk.

2. The combination of claim 1, wherein said securing means includes a circular hub having its inner face removably secured to said output shaft, the outer face of said hub having an annular recess formed therein and defining its outer marginal portion, said resilient disk and hacking and stiffening plates having centrally aligned openings formed therein, said recess being of a depth equal to the combined thickness of said resilient disk and said plates, the central portion of the outer face of said hub defined by said recess being received in said aligned openings, and means securing said resilient disk and said plates to said hub.

3. The combination of claim 1 wherein said resilient disk is of a diameter such that its outer peripheral edge coincides with the outer peripheral surfaces of at least a portion of said sidewalls.

References Cited in the file of this patent UNITED STATES PATENTS 1,951,105 Myers Mar. 13, 1934 2,410,812 Michel Nov. 12, 1946 2,527,762 Pratt Oct. 31, 1950 2,544,377 Cooke Mar. 6, 1951 2,722,090 Hasselquist Nov. 1, 1955 2,749,681l Reidenbach June 12, 1956 2,819,568 Kasick Jan. 14, 1958 FOREIGN PATENTS 424,173 Great Britain Feb. 15, 1935 

1. IN COMBINATION WITH A ROTARY SANDER OF THE TYPE HAVING A VERTICAL OUTPUT SHAFT WHOSE LOWER END IS ENCLOSED BY A GENERALLY CIRCULAR HOUSING HAVING UPSTANDING PERIPHERAL SIDE WALLS DEFINING A DOWNWARDLY OPENING RECESS, A SANDPAPER BACKING DISK, SAID BACKING DISK HAVING ONE SIDE ADAPTED TO HAVE A THIN DISK OF SANDPAPER SECURED THERETO, THE OTHER SIDE OF SAID BACKING DISK INCLUDING MEANS SECURING SAID DISK TO SAID OUTPUT SHAFT FOR ROTATION THEREWITH, SAID ONE SIDE COMPRISING THE OUTER SURFACE OF A THIN RESILIENT DISK, SAID DISK HAVING CIRCUMFERENTIALLY DISPOSED OPENINGS FORMED THEREIN, A PLURALITY OF GENERALLY RADIAL SLOTS FORMED THEREIN COMMUNICATING AT LEAST SOME OF SAID OPENINGS WITH THE OUTER PERIPHERAL EDGE OF SAID RESILIENT DISK, AND A THIN OUTER MARGINAL EDGE PORTION EXTENDING CLOSELY BENEATH THE LOWER EDGES OF SAID HOUSING, A CIRCULAR BACKING PLATE, THE INNER FACE OF SAID RESILIENT DISK BEING SECURED OVER THE OUTER FACE OF SAID BACKING PLATE, SAID BACKING PLATE BEING OF A DIAMETER SUBSTANTIALLY SMALLER THAN SAID RESILIENT DISK AND HAVING ITS OUTER PERIPHERAL EDGE PORTION DISPOSED INWARDLY OF SAID WALLS, SAID OPENINGS BEING OF A DIAMETER GREATER THAN THE WIDTH OF SAID SLOTS, SAID SLOTS BEING CURVED AND THEIR OUTER ENDS BEING ADAPTED TO TRAIL THE INNER ENDS THEREOF IN THE DIRECTION OF ROTATION OF SAID BACKING DISK, A CIRCULAR STIFFENING PLATE, THE INNER FACE OF SAID BACKING PLATE BEING SECURED OVER THE OUTER FACE OF SAID CIRCULAR STIFFENING PLATE, SAID STIFFENING PLATE BEING OF SUBSTANTIALLY SMALLER DIAMETER THAN SAID BACKING PLATE, SAID OPENINGS BEING DISPOSED INWARDLY OF THE OUTER PERIPHERAL PORTIONS OF SAID STIFFENING PLATE AND SAID STIFFENING PLATE AND SAID BACKING PLATE HAVING ALIGNED CIRCUMFERENTIALLY SPACED OPENINGS FORMED THERETHROUGH IN REGISTRY WITH SAID OPENINGS FORMED IN SAID RESILIENT DISK. 